1. Field of the Invention
The present invention relates to a display device and a method of manufacturing the display device. More particularly, the present invention relates to a display device capable of enhancing a display quality, and a method of manufacturing the display device, which enhances alignment accuracy between a lower substrate and an upper substrate of the display device.
2. Description of the Related Art
A liquid crystal display (LCD) device includes an LCD panel and a backlight assembly. The LCD panel includes a thin film transistor (TFT) substrate, a color filter substrate and a liquid crystal layer. The TFT substrate and the color filter substrate face each other. The liquid crystal layer is disposed between the TFT substrate and the color filter substrate. When electric fields are applied to the liquid crystal layer, an arrangement of liquid crystal molecules of the liquid crystal layer is altered to change optical transmissivity, thereby images are displayed on the LCD panel. The backlight assembly provides the LCD panel with light.
The TFT substrate includes a thin film transistor and a pixel electrode. The color filter substrate includes a black matrix, a color filter and a common electrode facing the pixel electrode of the TFT substrate.
The TFT substrate and the color filter substrate include a first alignment key and a second alignment key, respectively, for aligning the TFT substrate and the color filter substrate when the TFT substrate and the color filter substrate are assembled. The first alignment key of the TFT substrate is formed through a manufacturing process of a gate electrode of the TFT, or a manufacturing process of source and drain electrodes of the TFT. The second alignment key of the color filter substrate is formed through a manufacturing process of the black matrix.
After the first and second alignment keys are formed, many layers may be formed over the first and second alignment keys. During forming the layers, misalignment may occur. When accurate aligning is performed, a color filter of the color filter layer faces a pixel electrode of the TFT substrate. Many layers are formed and patterned over the first alignment key in order to form the pixel electrode after the first alignment key is formed, which may cause the pixel electrode to be misaligned with respect to the first alignment key. Therefore, when the TFT substrate and the color filter substrate are assembled by using the first and second alignment keys, the pixel electrode of the TFT substrate may deviate from the color filter of the color filter substrate.
In order to reduce misalignment of the TFT substrate and the color filter substrate, the first and second alignment keys are formed through a process of forming the pixel electrode of the TFT substrate and the common electrode of the color filter substrate, respectively. Then, the first and second alignment keys are formed through an optically transparent and electrically conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), etc. When the first and second alignment keys are formed through the optically transparent and electrically conductive material, the first and second alignment keys are transparent, so that an apparatus for detecting the first and second alignment keys cannot detect the first and second alignment keys.